When Nikki Haley offered the Republican response to President Obama’s final State of the Union, the American people heard an articulate conservative who has twice been elected Governor in South Carolina. It’s a sign of the GOP’s distemper that some conservatives denounced her because she didn’t denounce legal immigration.

Gov. Haley’s parents came to America from India. Her father taught botany at Voorhees College. Her mother started what would become a multimillion-dollar clothing company out of the living room of the family home. As she put it Tuesday, “I am the proud daughter of Indian immigrants who reminded my brothers, my sister and me every day how blessed we were to live in this country.”

Her conservative critics unloaded. “Trump should deport Nikki Haley” went one tweet. The next morning on “Fox & Friends,” Donald Trump declared that Gov. Haley is “very weak on immigration.”

Are we talking about the same Nikki Haley? The woman who says “illegal immigration is not welcome in South Carolina”? Who signed a law toughening the state’s illegal immigration reform act, which requires employers to verify the immigration status of new hires? Who has fought President Obama’s bid to resettle unvetted Syrian refugees? And whose state has joined 16 others in a lawsuit against Mr. Obama for what they say is his unconstitutional executive order on illegal immigration?

The distinction Gov. Haley is trying to make is between a functioning, legal immigration system that works in America’s interest—which Republicans say they want—and the unlawful, broken and arbitrary system that encourages illegality—which is what we now have and which President Obama exploits to the Democrats’ political advantage.

The attacks on Ms. Haley show that many on the right these days oppose any immigrants, even those who arrive legally. They also want to make opposition to immigration a GOP litmus test. A party that rejects Nikki Haley as a spokeswoman is one that doesn’t really want to build a governing majority.